Emergency laws have banned all public meetings and restricted media reporting.

Levon Ter-Petrosian, the defeated presidential candidate, has blamed police brutality for the violence.

Diplomatic intervention

Heikki Talvitie, a special envoy for the Organisation for Security and Cooperation in Europe (OSCE), when asked if a negotiation between the two sides was possible, said: "In all likeliness, this kind of dialogue between Ter-Petrosian and the government, at the moment, is not possible."

However, he said there was a possibility that both sides could negotiate in the days to come.

Talvitie said: "Let's not exclude it from the future."

Earlier, the envoy flew into Yerevan on Sunday and met Kocharian and Sarkisian for talks.

Talvitie also met the opposition groups in order to break the deadlock.

A US state department spokesman said Washington was sending Matt Bryza, deputy assistant secretary of state, to help "facilitate discussions" between the government and opposition.

But he stressed Bryza would not carry out "formal mediation".

Meanwhile, analysts say Armenia is heading for a period of uncertainty as neither side has shown much willingness to back down.

Petrosian has told his supporters not to rally during the 20-day emergency period.

However, he said he wass prepared to continue the protests afterwards.

A western diplomat said: "Petrosian is very determined and very charismatic. He'll find it difficult to step back from this now."